/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.dtstack.flink.sql.source.kafka.deserialization;

import com.dtstack.flink.sql.dirtyManager.manager.DirtyDataManager;
import com.dtstack.flink.sql.format.DeserializationMetricWrapper;
import com.dtstack.flink.sql.source.kafka.Calculate;
import com.dtstack.flink.sql.util.ReflectionUtils;
import org.apache.flink.api.common.serialization.DeserializationSchema;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.metrics.Gauge;
import org.apache.flink.metrics.MetricGroup;
import org.apache.flink.streaming.connectors.kafka.internal.KafkaConsumerThread;
import org.apache.flink.streaming.connectors.kafka.internals.AbstractFetcher;
import org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition;
import org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartitionState;
import org.apache.flink.types.Row;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.consumer.internals.SubscriptionState;
import org.apache.kafka.common.TopicPartition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Field;
import java.util.List;

import static com.dtstack.flink.sql.metric.MetricConstant.DT_PARTITION_GROUP;
import static com.dtstack.flink.sql.metric.MetricConstant.DT_TOPIC_GROUP;
import static com.dtstack.flink.sql.metric.MetricConstant.DT_TOPIC_PARTITION_LAG_GAUGE;

/**
 * add metric for source
 * <p>
 * company: www.dtstack.com
 * @author: toutian
 * create: 2019/12/24
 */
public class KafkaDeserializationMetricWrapper extends DeserializationMetricWrapper {

    private static final Logger LOG = LoggerFactory.getLogger(KafkaDeserializationMetricWrapper.class);

    private final Calculate calculate;

    public KafkaDeserializationMetricWrapper(
            TypeInformation<Row> typeInfo,
            DeserializationSchema<Row> deserializationSchema,
            Calculate calculate,
            DirtyDataManager dirtyDataManager) {
        super(typeInfo, deserializationSchema, dirtyDataManager);
        this.calculate = calculate;
    }

    protected void registerPtMetric(AbstractFetcher<Row, ?> fetcher) throws Exception {
        Field consumerThreadField = ReflectionUtils.getDeclaredField(fetcher, "consumerThread");
        consumerThreadField.setAccessible(true);
        KafkaConsumerThread consumerThread = (KafkaConsumerThread) consumerThreadField.get(fetcher);

        Field hasAssignedPartitionsField = consumerThread.getClass().getDeclaredField("hasAssignedPartitions");
        hasAssignedPartitionsField.setAccessible(true);

        // get subtask unassigned kafka topic partition
        Field subscribedPartitionStatesField = ReflectionUtils.getDeclaredField(fetcher, "subscribedPartitionStates");
        subscribedPartitionStatesField.setAccessible(true);
        List<KafkaTopicPartitionState<KafkaTopicPartition>> subscribedPartitionStates = (List<KafkaTopicPartitionState<KafkaTopicPartition>>) subscribedPartitionStatesField.get(fetcher);

        // init partition lag metric
        for (KafkaTopicPartitionState<KafkaTopicPartition> kafkaTopicPartitionState : subscribedPartitionStates) {
            KafkaTopicPartition kafkaTopicPartition = kafkaTopicPartitionState.getKafkaTopicPartition();
            MetricGroup topicMetricGroup = getRuntimeContext().getMetricGroup().addGroup(DT_TOPIC_GROUP, kafkaTopicPartition.getTopic());

            MetricGroup metricGroup = topicMetricGroup.addGroup(DT_PARTITION_GROUP, kafkaTopicPartition.getPartition() + "");
            metricGroup.gauge(DT_TOPIC_PARTITION_LAG_GAUGE, new Gauge<Long>() {
                // tmp variable
                boolean initLag = true;
                int partitionIndex;
                SubscriptionState subscriptionState;
                TopicPartition topicPartition;

                @Override
                public Long getValue() {
                    // first time register metrics
                    if (initLag) {
                        partitionIndex = kafkaTopicPartition.getPartition();
                        initLag = false;
                        return -1L;
                    }
                    // when kafka topic partition assigned calc metrics
                    if (subscriptionState == null) {
                        try {
                            Field consumerField = consumerThread.getClass().getDeclaredField("consumer");
                            consumerField.setAccessible(true);

                            KafkaConsumer kafkaConsumer = (KafkaConsumer) consumerField.get(consumerThread);
                            Field subscriptionStateField = kafkaConsumer.getClass().getDeclaredField("subscriptions");
                            subscriptionStateField.setAccessible(true);

                            boolean hasAssignedPartitions = (boolean) hasAssignedPartitionsField.get(consumerThread);

                            if (!hasAssignedPartitions) {
                                LOG.error("wait 50 secs, but not assignedPartitions");
                            }

                            subscriptionState = (SubscriptionState) subscriptionStateField.get(kafkaConsumer);

                            topicPartition = subscriptionState
                                    .assignedPartitions()
                                    .stream()
                                    .filter(x -> x.partition() == partitionIndex)
                                    .findFirst()
                                    .get();

                        } catch (Exception e) {
                            LOG.error(e.getMessage());
                        }
                        return -1L;
                    } else {
                        return calculate.calc(subscriptionState, topicPartition);
                    }
                }
            });
        }
    }

    public void setFetcher(AbstractFetcher<Row, ?> fetcher) {
        try {
            registerPtMetric(fetcher);
        } catch (Exception e) {
            LOG.error("register topic partition metric error.", e);
        }
    }
}
